Random FTM duh question.. Pumping

I know most people are probably going to say a big ol DUHHHH but I don't know exactly how this works. So when you pump breast milk, you store it in the little bags and label date and time.. Do they then go directly into the freezer? Or can you refrigerate for certain amount of time? If frozen, you defrost it (?) when you need it, pour it into a bottle, then heat it up? How to defrost (overnight in fridge)? What if you need to defrost quickly - is that safe? I have a bottle warmer... Will that get defrosted milk to right temp? I will always double check of course.